The principal objectives of this work are to obtain a better understanding of presently available implant packages, encapsulants, sealants and insulators, to improve their characteristics, and if necessary, to develop new materials for specific neural prosthetic applications. The Contractor shall evaluate potential implant packages, encapsulants, sealants and lead insulators for the following factors if such information is relevant to the intended uses, and if such information is not prsently available. Evaluate combinations of materials applied in layers. Materials to be evaluated shall include members of the Parylene and silicone rubber families but should no be restricted to these. Determine specifications for medical grades of the materials if medical grades are not available.